The background description provided herein is for the purpose of generally presenting the context of the present disclosure. The subject matter discussed in the background of the disclosure should not be assumed to be prior art merely as a result of its mention in the background of the disclosure. Similarly, a problem mentioned in the background of the disclosure or associated with the subject matter of the background of the disclosure should not be assumed to have been previously recognized in the prior art. The subject matter in the background of the disclosure merely represents different approaches, which in and of themselves may also be disclosures. Work of the presently named inventor(s)/applicant(s), to the extent it is described in the background of the disclosure, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
LCDs are widely used in electronic devices, such as laptops, smart phones, digital cameras, billboard-type displays, and high-definition televisions.
LCD panels may be configured as disclosed, for example, in Wu et al., U.S. Pat. No. 6,956,631, which is assigned to AU Optronics Corp., the parent company of the assignee of the current application, and hereby incorporated by reference in its entirety. As disclosed in Wu et al. FIG. 1, the LCD panel may comprise a top polarizer, a lower polarizer, a liquid crystal cell, and a back light. Light from the back light passes through the lower polarizer, through the liquid crystal cell, and then through the top polarizer. As further disclosed in Wu et al. FIG. 1, the liquid crystal cell may comprise a lower glass substrate and an upper substrate containing color filters. A plurality of pixels comprising thin film transistor (TFT) devices may be formed in an array on the glass substrate, and a liquid crystal compound may be filled into the space between the glass substrate and the color filter forming a layer of liquid crystal material.
As further disclosed in Wu et al., a hardening protective layer may be placed on the top polarizer, to protect the top polarizer from scratching during the assembly process. To reduce glare and improve the contrast of the display, one or more anti-glaring treatments, such as an anti-reflective film, may be included in the panel. As disclosed in Wu et al., it may be advantageous to apply the anti-glaring treatment to the lower polarizer, so as to reduce undesirable optical effects, such as browning, glittering, and decreased contrast ratio.
As explained in Sawasaki et al., U.S. Pat. No. 7,557,895, which is assigned to AU Optronics Corp., the parent company of the assignee of the current application, and hereby incorporated by reference in its entirety, the thickness of the liquid crystal layer typically must be uniformly controlled, in order to avoid unevenness in brightness across the LCD panel. As disclosed in Sawasaki et al., the required uniformity may be achieved by disposing a plurality of pillar spacers between the TFT substrate and the color filter substrate. As further disclosed in Sawasaki et al., the pillar spacers may be formed with different heights, such that some spacers have a height that is greater than the gap between the substrates and other spacers have a height that is less than the gap between the substrates. This configuration may permit the spacing between the substrates to vary with temperature changes but also prevent excessive deformation when forces are applied to the panel.
Sawasaki et al. further discloses a method for assembling the substrates with the liquid crystal material between them. This method comprises steps of preparing the two substrates, coating a sealing material on the circumference of the outer periphery of one of the pair of substrates, dropping an appropriate volume of liquid crystal on one of the pair of substrates, and filling in the liquid crystal between the pair of substrates by attaching the pair of substrates in a vacuum followed by returning the attached pair of substrates to atmospheric pressure.
The TFTs, gate and data lines, and pixel electrodes may be formed in a multilayer structure such as that shown in FIGS. 1 and 2E of Lai et al., U.S. Pat. No. 7,170,092 and in its division U.S. Pat. No. 7,507,612, both of which are assigned to AU Optronics Corp., the parent company of the assignee of the current application, and both of which are hereby incorporated by reference in their entireties. The multilayer structure may comprise a first conducting layer, a first insulating layer, a semiconductor layer, a doped semiconductor layer, and a second conducting layer disposed in sequence on the substrate. It may further comprise a second insulating layer and a pixel electrode disposed on the second insulating layer. The first conducting layer may comprise at least one of a gate line or a gate electrode. The doped semiconductor layer may comprise a source and a drain. The second conducting layer may comprise a source electrode and a drain electrode. The multilayer structure may be formed using a series of wet and dry etching processes, for example as disclosed in Lai et al. FIGS. 2A-2D.
Additional techniques for forming TFTs are disclosed in Chen, U.S. Pat. No. 7,652,285, which is assigned to AU Optronics Corp., the parent company of the assignee of the current application, and hereby incorporated by reference in its entirety. As disclosed in Chen, to form the channel of the TFT, the second metal layer is etched in order to open a portion of the second metal layer over the gate electrode and to separate the source region and drain region. This etching can be performed in multiple ways, including the back-channel etching process disclosed for example in Chen FIGS. 2A-2E and the etch stop process disclosed for example in Chen FIGS. 5A-5D and 6.
Chen discloses that TFT leakage currents may be reduced by adding a spacer layer formed at the sidewalls of the conductive amorphous silicon layer, isolating the conductive amorphous silicon layer from the insulating layer. Chen discloses that this spacer layer can be formed by oxidizing the exposed surface of the conductive amorphous silicon layer after the etch of the second metal layer is performed. Chen discloses that this surface may be oxidized by a number of different techniques, including oxygen plasma ashing, or the use of ozone plasma in the presence of carbon tetrafluoride and sulfur hexafluoride gases.
As disclosed in Tsujimura et al., U.S. Pat. No. 6,689,629, which is assigned to AU Optronics Corp., the parent company of the assignee of the current application, and hereby incorporated by reference in its entirety, the wirings, such as the scan lines and signal lines of the array, are preferably comprised of a low-resistance material, such as aluminum or an aluminum alloy, so as to increase the speed with which the scan lines and signal lines operate. However, aluminum tends to be easily oxidized. For that reason, Tsujimura et al. discloses forming wirings as a two-layer structure, with a lower layer of aluminum, aluminum alloy or other low-resistance material, and an upper layer of molybdenum, chromium, tantalum, titanium, alloys thereof, or oxidation-resistant conductive material.
Tsujimura further discloses that the scan lines and signal lines contact connection pads, through which the array is connected to a driving system. Tsujimura discloses forming dummy conductive patterns, situated between the connection pads and the pixel electrodes, but not in contact with any of the wirings on the substrate. By increasing the density of conductive material in a given area, the dummy conductive patterns can reduce etching undercut and improve the tapered shape of the wiring.
An LCD backlight structure may include optical films. As disclosed in Fu et al., U.S. Pat. No. 7,125,157, which is assigned to AU Optronics Corp., the parent company of the assignee of the current application, and hereby incorporated by reference in its entirety, the optical films fixed to the backlight unit may expand or contract as temperature varies. In addition, some LCDs are rotatable between different angles. As the LCD is rotated, the weight of the optical films may be concentrated at single fixing points, resulting in stress and deformation of the optical films. Fu et al. discloses a supporting mechanism for the optical films that addresses these issues. The backlight frame comprises a plurality of supporting portions which may, for example, be formed as protrusions, cylinders, or cuboids. The film comprises a plurality of constraining portions which may, for example, be holes or grooves and may be circular, elliptical, rectangular, rectangular with rounded corners, or polygonal in shape. One or more of the supporting portions make contact with constraining portions and thereby support the optical films. As the position of the LCD is changed, for example by rotation, different supporting portions will be in contact with constraining portions and providing the required support.
In LCD panels, the semiconductor material making up the TFT channel may be amorphous silicon. However, as disclosed in Chen, U.S. Pat. No. 6,818,967, which is assigned to AU Optronics Corp., the parent company of the assignee of the current application, and hereby incorporated by reference in its entirety, poly-silicon channel TFTs offer advantages over amorphous silicon TFTs, including lower power and greater electron migration rates. As disclosed in Chen, the re-crystallization process of LTPS results in the formation of mounds on the surface of the poly-silicon layer, and these mounds impact the current characteristics of the LTPS TFT. Chen discloses a method to reduce the size of the LTPS surface mounds, by performing a first anneal treatment, then performing a surface etching treatment, for example using a solution of hydrofluoric acid, and then performing a second anneal treatment. The resulting LTPS surface has mounds with a height/width ratio of less than 0.2. A gate isolation layer, gate, dielectric layer, and source and drain metal layers can then be deposited above the LTPS layer to form a complete LTPS TFT.
For the current TFT-LCD, except for a ring of sealant around the boarder of the liquid crystal cell, the top and bottom substrates are separated. When the cell is bended for a curved display, the top and bottom substrates will shift laterally for a different amount, causing a lot of problems such as light leakage, mura, yellowish, poor transmittance, color mixing and so on.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.